This invention relates to a roller bearing.
FIGS. 4 to 6 show conventional shell type needle roller bearings. The one shown in FIG. 4 has a cage 2. A plurality of needle rollers 3 are arranged in the outer ring 1 along a raceway formed on inner periphery thereof, kept apart a predetermined distance from each other by the cage 2.
The one shown in FIG. 5 is a full type roller bearing. Its rollers 3 are arranged circumferentially close to each other. Grease filling the space between the rollers serves to keep the rollers on the inner periphery of the outer ring 1 by its adhesive force, preventing the rollers from dropping out.
The bearing shown in FIG. 6 is another full type bearing. Its outer ring 1 has inwardly bent portions 4 at both ends to prevent the rollers 3 from dropping out.
Since the bearing shown in FIG. 4 has the cage 2 for guiding the rollers 3, its maximum revolving speed is high and its rollers 3 will never skew. But due to the very presence of the cage, it is difficult to increase the number of rollers used and their length and thus to increase the load-bearing capacity of the bearing. Namely, in order to increase both the number of rollers used and their length, the cage has to have a larger number of pockets. Such a cage is not only difficult to manufacture and thus costly but it is also very fragile.
Problems of the full type bearings are that a rather large friction is produced between the rollers and that the rollers are skewed very easily. Thus, their use is limited. Another problem of the bearing that uses grease to hold the roller in position is that the rollers 3 tend to drop out when handling the bearing.
It is therefore an object of this invention to solve the problems of conventional full type roller bearings, including the problems of large friction between rollers and the skewing of rollers, and to increase the load-bearing capacity of the bearing by using a larger number of longer rollers than those of a conventional cage-carrying bearing.